Exercise and the right ventricle: a potential Achilles' heel

The athletes heart-from acute stimulus to chronic adaptation

INTRODUCTION

The complex phenomenon of the athlete's heart (AH) describes the chronic physiological structural and functional adaptation secondary to repeated exposure of an acute exercise stimulus.

SOURCES OF DATA

This narrative review is based on published evidence.

AREAS OF AGREEMENT

Highly trained athletic individuals frequently display cardiac parameters which are suggestive of an AH and can exceed the traditional 'normal' limits.

AREA OF CONTROVERSY

The physiological processes underpinning the extent of cardiac adaption and how this is closely linked to exercise type, but also sex, ethnicity, and body size.

GROWING POINTS

Since its seminal description by Morganroth and colleagues in 1975, our understanding of the AH has evolved in tandem with improvements in cardiac imaging techniques alongside the exploration of more diverse athletic populations. This narrative review aims to provide a balanced discussion of the multi-factorial nature of structure and function of the AH with specific reference to the unique physiological exercise stimuli.

AREAS TIMELY FOR DEVELOPING RESEARCH

Despite great interest in cardiac adaptations across a broad spectrum of athletic populations, future research designs should consider the use of new and novel imaging techniques to enhance our understanding of the acute cardiovascular responses which ultimately mediates such adaptations, especially in athletic populations underrepresented in the literature.

Device-measured physical activity and cardiac structure by magnetic resonance

BACKGROUND AND AIMS

Although extreme cardiac adaptions mirroring phenotypes of cardiomyopathy have been observed in endurance athletes, adaptions to high levels of physical activity within the wider population are under-explored. Therefore, in this study, associations between device-measured physical activity and clinically relevant cardiac magnetic resonance volumetric indices were investigated.

METHODS

Individuals without known cardiovascular disease or hypertension were included from the UK Biobank. Cardiac magnetic resonance data were collected between 2015 and 2019, and measures of end-diastolic chamber volume, left ventricular (LV) wall thickness, and LV ejection fraction were extracted. Moderate-to-vigorous-intensity physical activity (MVPA), vigorous-intensity physical activity (VPA), and total physical activity were assessed via wrist-worn accelerometers.

RESULTS

A total of 5977 women (median age and MVPA: 62 years and 46.8 min/day, respectively) and 4134 men (64 years and 49.8 min/day, respectively) were included. Each additional 10 min/day of MVPA was associated with a 0.70 [95% confidence interval (CI): 0.62, 0.79] mL/m2 higher indexed LV end-diastolic volume (LVEDVi) in women and a 1.08 (95% CI: 0.95, 1.20) mL/m2 higher LVEDVi in men. However, even within the top decile of MVPA, LVEDVi values remained within the normal ranges [79.1 (95% CI: 78.3, 80.0) mL/m2 in women and 91.4 (95% CI: 90.1, 92.7) mL/m2 in men]. Associations with MVPA were also observed for the right ventricle and the left/right atria, with an inverse association observed for LV ejection fraction. Associations of MVPA with maximum or average LV wall thickness were not clinically meaningful. Results for total physical activity and VPA mirrored those for MVPA.

CONCLUSIONS

High levels of device-measured physical activity were associated with cardiac remodelling within normal ranges.

Effects of hemodynamic load on cardiac remodeling in fish and mammals: the value of comparative models

The ability of the vertebrate heart to remodel enables the cardiac phenotype to be responsive to changes in physiological conditions and aerobic demand. Examples include exercise-induced cardiac hypertrophy, and the significant remodeling of the trout heart during thermal acclimation. Such changes are thought to occur in response to a change in hemodynamic load (i.e. the forces that the heart must work against to circulate blood). Variations in hemodynamic load are caused by either a volume overload (high volume of blood returning to the heart, impairing contraction) or a pressure overload (elevated afterload pressure that the heart must contract against). The changes observed in the heart during remodeling are regulated by multiple cellular signaling pathways. The cardiac response to these regulatory mechanisms occurs across levels of biological organization, affecting cardiac morphology, tissue composition and contractile function. Importantly, prolonged exposure to pressure overload can cause a physiological response - that improves function - to transition to a pathological response that causes loss of function. This Review explores the role of changes in hemodynamic load in regulating the remodeling response, and considers the cellular signals responsible for regulating remodeling, incorporating knowledge gained from studying biomedical models and comparative animal models. We specifically focus on the renin-angiotensin system, and the role of nitric oxide, oxygen free radicals and transforming growth factor beta. Through this approach, we highlight the strong conservation of the regulatory pathways of cardiac remodeling, and the specific conditions within endotherms that may be conducive to the development of pathological phenotypes.

Histological evaluation of cardiac remodelling in equine athletes

Approximately 1-2 per 100,000 young athletes die from sudden cardiac death (SCD) and extreme exercise may be associated with myocardial scar and arrhythmias. Racehorses have a high prevalence of atrial fibrillation (AF) and SCD but the presence of myocardial scar and inflammation has not been evaluated. Cardiac tissues from the left (LAA) and right (RAA) atrial appendages, left ventricular anterior (LVAPM) and posterior (LVPPM) papillary muscles, and right side of the interventricular septum (IVS-R) were harvested from racehorses with sudden cardiac death (SCD, n = 16) or other fatal injuries (OFI, n = 17), constituting the athletic group (ATH, n = 33), and compared to sedentary horses (SED, n = 10). Horses in the ATH group had myocyte hypertrophy at all sites; increased fibrosis at all sites other than the LAA; increased fibroblast infiltration but a reduction in the overall extracellular matrix (ECM) volume in the RAA, LVAPM, and IVS-R compared to SED horses. In this horse model, athletic conditioning was associated with myocyte hypertrophy and a reduction in ECM. There was an excess of fibrocyte infiltration and focal fibrosis that was not present in non-athletic horses, raising the possibility of an exercise-induced pro-fibrotic substrate.

Revealing the true nature of a parachute mitral valve during an ultra-trail race

Pre-participation screening and management of congenital cardiac valvulopathy in competitive athletes can be challenging, particularly within the context of ultra-endurance disciplines. A 55-year-old female athlete without a reported history of cardiac disease exhibited clinical signs of cardiogenic pulmonary edema during a 156 km ultra-trail race. The echocardiographic assessment revealed the presence of a parachute mitral valve, with no evidence of mitral stenosis or regurgitation at rest, but it demonstrated severe dynamic mitral stenosis during exercise. In competitive athletes, the detection of rare valvulopathy should prompt a comprehensive cardiac evaluation aimed at assessing the potential for dynamic valvular dysfunction.

Endurance Training Provokes Arrhythmogenic Right Ventricular Cardiomyopathy Phenotype in Heterozygous Desmoglein-2 Mutants: Alleviation by Preload Reduction

Desmoglein-2 mutations are detected in 5-10% of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). Endurance training accelerates the development of the ARVC phenotype, leading to earlier arrhythmic events. Homozygous Dsg2 mutant mice develop a severe ARVC-like phenotype. The phenotype of heterozygous mutant (Dsg2mt/wt) or haploinsufficient (Dsg20/wt) mice is still not well understood. To assess the effects of age and endurance swim training, we studied cardiac morphology and function in sedentary one-year-old Dsg2mt/wt and Dsg20/wt mice and in young Dsg2mt/wt mice exposed to endurance swim training. Cardiac structure was only occasionally affected in aged Dsg20/wt and Dsg2mt/wt mice manifesting as small fibrotic foci and displacement of Connexin 43. Endurance swim training increased the right ventricular (RV) diameter and decreased RV function in Dsg2mt/wt mice but not in wild types. Dsg2mt/wt hearts showed increased ventricular activation times and pacing-induced ventricular arrhythmia without obvious fibrosis or inflammation. Preload-reducing therapy during training prevented RV enlargement and alleviated the electrophysiological phenotype. Taken together, endurance swim training induced features of ARVC in young adult Dsg2mt/wt mice. Prolonged ventricular activation times in the hearts of trained Dsg2mt/wt mice are therefore a potential mechanism for increased arrhythmia risk. Preload-reducing therapy prevented training-induced ARVC phenotype pointing to beneficial treatment options in human patients.

The Acute Impact of Endurance Exercise on Right Ventricular Structure and Function: A Systematic Review and Meta-analysis

There have been many studies since the late 1980s investigating the effect of endurance exercise on the left ventricle. More recently, attention has shifted to the right heart, with suggestions that endurance exercise may have a detrimental effect on the right ventricle. This systematic review and meta-analysis summarizes and critiques 26 studies, including 649 athletes, examining the acute impact of endurance exercise on the right ventricle. We also present a subanalysis contrasting ultraendurance with endurance exercise. Finally, we identify areas for future research, such as the influence of sex, ethnicity, and age.

Prevalence and Clinical Significance of Electrocardiographic Complete Right Bundle Branch Block in Young Individuals

BACKGROUND AND AIMS

There is limited information on the clinical significance of complete right bundle branch block (CRBBB) in young individuals. The aim of this study was to determine the prevalence and significance of CRBBB in a large cohort of young individuals aged 14-35 years old.

METHODS

From 2008 to 2018, 104,369 consecutive individuals underwent a cardiovascular assessment with a health questionnaire, electrocardiogram, clinical consultation, and selective echocardiography. Follow-up was obtained via direct telephone consultations. Mean follow-up was 7.3 ± 2.7 years.

RESULTS

CRBBB was identified in 154 (0.1%) individuals and was more prevalent in males compared with females (0.20% vs. 0.06%; p<0.05) and in athletes compared with non-athletes (0.25% vs. 0.14%; p<0.05). CRBBB-related cardiac conditions were identified in 7 (5%) individuals (4 with atrial septal defect, 1 with Brugada syndrome, 1 with progressive cardiac conduction disease and 1 with atrial fibrillation). Pathology was more frequently identified in individuals with non-isolated CRBBB compared with individuals with isolated CRBBB (14% vs 1%; p < 0.05) and in individuals with a QRS duration of ≥130 milliseconds (ms) compared with individuals with a QRS of <130ms (10% vs 1%; p<0.05).

CONCLUSION

The prevalence of CRBBB in young individuals was 0.1% and was more prevalent in males and athletes. CRBBB-related conditions were identified in 5% of individuals and were more common in individuals with non-isolated CRBBB and more pronounced intraventricular conduction delay (QRS duration of ≥130ms). Secondary evaluation should be considered for young individuals with CRBBB with symptoms, concerning family history, additional electrocardiographic anomalies or significant QRS prolongation (≥130ms).

Is the Lung Built for Exercise? Advances and Unresolved Questions

ABSTRACT

Nearly 40 yr ago, Professor Dempsey delivered the 1985 ACSM Joseph B. Wolffe Memorial Lecture titled: "Is the lung built for exercise?" Since then, much experimental work has been directed at enhancing our understanding of the functional capacity of the respiratory system by applying complex methodologies to the study of exercise. This review summarizes a symposium entitled: "Revisiting 'Is the lung built for exercise?'" presented at the 2022 American College of Sports Medicine annual meeting, highlighting the progress made in the last three-plus decades and acknowledging new research questions that have arisen. We have chosen to subdivide our topic into four areas of active study: (i) the adaptability of lung structure to exercise training, (ii) the utilization of airway imaging to better understand how airway anatomy relates to exercising lung mechanics, (iii) measurement techniques of pulmonary gas exchange and their importance, and (iv) the interactions of the respiratory and cardiovascular system during exercise. Each of the four sections highlights gaps in our knowledge of the exercising lung. Addressing these areas that would benefit from further study will help us comprehend the intricacies of the lung that allow it to meet and adapt to the acute and chronic demands of exercise in health, aging, and disease.

Right Ventricle and Epigenetics: A Systematic Review

There is an increasing recognition of the crucial role of the right ventricle (RV) in determining the functional status and prognosis in multiple conditions. In the past decade, the epigenetic regulation (DNA methylation, histone modification, and non-coding RNAs) of gene expression has been raised as a critical determinant of RV development, RV physiological function, and RV pathological dysfunction. We thus aimed to perform an up-to-date review of the literature, gathering knowledge on the epigenetic modifications associated with RV function/dysfunction. Therefore, we conducted a systematic review of studies assessing the contribution of epigenetic modifications to RV development and/or the progression of RV dysfunction regardless of the causal pathology. English literature published on PubMed, between the inception of the study and 1 January 2023, was evaluated. Two authors independently evaluated whether studies met eligibility criteria before study results were extracted. Amongst the 817 studies screened, 109 studies were included in this review, including 69 that used human samples (e.g., RV myocardium, blood). While 37 proposed an epigenetic-based therapeutic intervention to improve RV function, none involved a clinical trial and 70 are descriptive. Surprisingly, we observed a substantial discrepancy between studies investigating the expression (up or down) and/or the contribution of the same epigenetic modifications on RV function or development. This exhaustive review of the literature summarizes the relevant epigenetic studies focusing on RV in human or preclinical setting.

Aged gastrocnemius muscle of mice positively responds to a late onset adapted physical training

Introduction: A regular physical training is known to contribute to preserve muscle mass and strength, maintaining structure and function of neural and vascular compartments and preventing muscle insulin resistance and inflammation. However, physical activity is progressively reduced during aging causing mobility limitations and poor quality of life. Although physical exercise for rehabilitation purposes (e.g., after fractures or cardiovascular events) or simply aiming to counteract the development of sarcopenia is frequently advised by physicians, nevertheless few data are available on the targets and the global effects on the muscle organ of adapted exercise especially if started at old age. Methods: To contribute answering this question for medical translational purposes, the proteomic profile of the gastrocnemius muscle was analyzed in 24-month-old mice undergoing adapted physical training on a treadmill for 12 weeks or kept under a sedentary lifestyle condition. Proteomic data were implemented by morphological and morphometrical ultrastructural evaluations. Results and Discussion: Data demonstrate that muscles can respond to adapted physical training started at old age, positively modulating their morphology and the proteomic profile fostering protective and saving mechanisms either involving the extracellular compartment as well as muscle cell components and pathways (i.e., mitochondrial processes, cytoplasmic translation pathways, chaperone-dependent protein refolding, regulation of skeletal muscle contraction). Therefore, this study provides important insights on the targets of adapted physical training, which can be regarded as suitable benchmarks for future in vivo studies further exploring the effects of this type of physical activity by functional/metabolic approaches.

The Pulmonary Vasculature

The pulmonary circulation is a low-pressure, low-resistance circuit whose primary function is to deliver deoxygenated blood to, and oxygenated blood from, the pulmonary capillary bed enabling gas exchange. The distribution of pulmonary blood flow is regulated by several factors including effects of vascular branching structure, large-scale forces related to gravity, and finer scale factors related to local control. Hypoxic pulmonary vasoconstriction is one such important regulatory mechanism. In the face of local hypoxia, vascular smooth muscle constriction of precapillary arterioles increases local resistance by up to 250%. This has the effect of diverting blood toward better oxygenated regions of the lung and optimizing ventilation-perfusion matching. However, in the face of global hypoxia, the net effect is an increase in pulmonary arterial pressure and vascular resistance. Pulmonary vascular resistance describes the flow-resistive properties of the pulmonary circulation and arises from both precapillary and postcapillary resistances. The pulmonary circulation is also distensible in response to an increase in transmural pressure and this distention, in addition to recruitment, moderates pulmonary arterial pressure and vascular resistance. This article reviews the physiology of the pulmonary vasculature and briefly discusses how this physiology is altered by common circumstances.

Influence of exercise training on the left atrium: implications for atrial fibrillation, heart failure, and stroke

The left atrium (LA) plays a critical role in receiving pulmonary venous return and modulating left ventricular (LV) filling. With the onset of exercise, LA function contributes to the augmentation in stroke volume. Due to the growing focus on atrial imaging, there is now evidence that structural remodeling and dysfunction of the LA is associated with adverse outcomes including incident cardiovascular disease. In patients with established disease, pathological changes in atrial structure and function are associated with exercise intolerance, increased hospital admissions and mortality, independent of left ventricular function. Exercise training is widely recommended in patients with cardiovascular disease to improve patient outcomes and maintain functional capacity. There are widely documented changes in LV function with exercise, yet less attention has been given to the LA. In this review, we first describe LA physiology at rest and during exercise, before exploring its association with cardiac disease outcomes including atrial fibrillation, heart failure, and stroke. The adaptation of the LA to short- and longer-term exercise training is evaluated through review of longitudinal studies of exercise training in healthy participants free of cardiovascular disease and athletes. We then consider the changes in LA structure and function among patients with established disease, where adverse atrial remodeling may be implicated in the disease process. Finally, we consider important future directions for assessment of atrial structure and function using novel imaging modalities, in response to acute and chronic exercise.

Normative values of non-invasively assessed RV function and pulmonary circulation coupling for pre-participation screening derived from 497 male elite athletes

BACKGROUND

Reference values for right ventricular function and pulmonary circulation coupling were recently established for the general population. However, normative values for elite athletes are missing, even though exercise-related right ventricular enlargement is frequent in competitive athletes.

METHODS

We examined 497 healthy male elite athletes (age 26.1 ± 5.2 years) of mixed sports with a standardized transthoracic echocardiographic examination. Tricuspid annular plane excursion (TAPSE) and systolic pulmonary artery pressure (SPAP) were measured. Pulmonary circulation coupling was calculated as TAPSE/SPAP ratio. Two age groups were defined (18-29 years and 30-39 years) and associations of clinical parameters with the TAPSE/SPAP ratio were determined and compared for each group.

RESULTS

Athletes aged 18-29 (n = 349, 23.8 ± 3.5 years) displayed a significantly lower TAPSE/SPAP ratio (1.23 ± 0.3 vs. 1.31 ± 0.33 mm/mmHg, p = 0.039), TAPSE/SPAP to body surface area (BSA) ratio (0.56 ± 0.14 vs. 0.6 ± 0.16 mm*m2/mmHg, p = 0.017), diastolic blood pressure (75.6 ± 7.9 vs. 78.8 ± 10.7 mmHg, p < 0.001), septal wall thickness (10.2 ± 1.1 vs. 10.7 ± 1.1 mm, p = 0.013) and left atrial volume index (27.5 ± 4.5 vs. 30.8 ± 4.1 ml/m2, p < 0.001), but a higher SPAP (24.2 ± 4.5 vs. 23.2 ± 4.4 mmHg, p = 0.035) compared to athletes aged 30-39 (n = 148, 33.1 ± 3.4 years). TAPSE was not different between the age groups. The TAPSE/SPAP ratio was positively correlated with left ventricular stroke volume (r = 0.133, p = 0.018) and training amount per week (r = 0.154, p = 0.001) and negatively correlated with E/E' lat. (r = -0.152, p = 0.005).

CONCLUSION

The reference values for pulmonary circulation coupling determined in this study could be used to interpret and distinguish physiological from pathological cardiac remodeling in male elite athletes.

Mitral and Tricuspid Valve Disease in Athletes

Observing mitral or tricuspid valve disease in an athlete raises many considerations for the clinician. Initially, the etiology must be clarified, with causes differing depending on whether the athlete is young or a master. Notably, vigorous training in competitive athletes leads to a constellation of structural and functional adaptations involving cardiac chambers and atrioventricular valve systems. In addition, a proper evaluation of the athlete with valve disease is necessary to evaluate the eligibility for competitive sports and identify those requiring more follow-up. Indeed, some valve pathologies are associated with an increased risk of severe arrhythmias and potentially sudden cardiac death. Traditional and advanced imaging modalities help clarify clinical doubts, allowing essential information about the athlete's physiology and differentiating between primary valve diseases from those secondary to training-related cardiac adaptations. Remarkably, another application of multimodality imaging is evaluating athletes with valve diseases during exercise to reproduce the sport setting and better characterize the etiology and valve defect mechanism. This review aims to analyze the possible causes of atrioventricular valve diseases in athletes, focusing primarily on imaging applications in diagnosis and risk stratification.

Körperliche Aktivität/Sport – Auswirkung unterschiedlicher Trainingsformen und -intensitäten auf das Herz

„Das Sport-Paradox“ beschreibt die Ambivalenz zwischen einerseits klar evidenzbasierten gesundheitlichen Vorteilen des regelmäßigen Sporttreibens und andererseits der ebenso unumstrittenen gesundheitlichen Nachteile, die der Sport mit sich bringen kann.

Mindestens 30 Minuten moderate körperliche Belastung (bei Kindern 60 Minuten), an mindesten 5 Tagen pro Woche sind notwendig, um die gesundheitlichen Vorteile zu erreichen. Das Herz-Kreislaufsystem unterliegt dabei, bei regelmäßigem intensiven, vor allem dynamischem Ausdauertraining physiologischen Adapationen, welche von verschiedenen weiteren Faktoren abhängen. Während die exzentrische Hypertrophie des linken Ventrikels, in der Regel, reversibel ist, zeigt sich die „right ventricular fatigue“, bei entsprechender genetischer Belastung teilweise progredient. Dilatation und Fibrosierung der Vorhöfe führen zu einem erhöhten Risiko für ein Vorhofflimmern und auch eine häufig klinisch asymptomatische Dilatation der Aorta oder eine durch chronischen Stress bedingte Koronarsklerose können potenziell schwerwiegende Folgen mit sich bringen. Umso entscheidender sind individuelle und spezifische Trainingsempfehlungen.

Dynamic mechanobiology of cardiac cells and tissues: Current status and future perspective

Mechanical forces impact cardiac cells and tissues over their entire lifespan, from development to growth and eventually to pathophysiology. However, the mechanobiological pathways that drive cell and tissue responses to mechanical forces are only now beginning to be understood, due in part to the challenges in replicating the evolving dynamic microenvironments of cardiac cells and tissues in a laboratory setting. Although many in vitro cardiac models have been established to provide specific stiffness, topography, or viscoelasticity to cardiac cells and tissues via biomaterial scaffolds or external stimuli, technologies for presenting time-evolving mechanical microenvironments have only recently been developed. In this review, we summarize the range of in vitro platforms that have been used for cardiac mechanobiological studies. We provide a comprehensive review on phenotypic and molecular changes of cardiomyocytes in response to these environments, with a focus on how dynamic mechanical cues are transduced and deciphered. We conclude with our vision of how these findings will help to define the baseline of heart pathology and of how these in vitro systems will potentially serve to improve the development of therapies for heart diseases.

Investigating the roles of exercise intensity and biological sex on postexercise alterations in cardiac function

The term exercise-induced cardiac fatigue (EICF) has typically been used to describe a transient reduction in cardiac function following prolonged-strenuous exercise. Recent evidence demonstrates that EICF can occur following only 45 min of high-intensity exercise when assessed using exercising stress echocardiography. This investigation sought to examine whether sprint intervals (SIT; 6 × 30 s Wingate tests), or 90-min moderate-cycling with sprint intervals (MIX; 90 min with 1 × 30 s Wingate test every 15 min) would cause greater EICF than 90 min (CON) or 3 h (LONG) moderate-cycling assessed using stress echocardiography, with a secondary aim to interrogate sex differences in EICF. Seventeen participants (M: 9, F: 8) underwent three cycling sessions with stress-echocardiography performed before-and-after each condition at a target heart rate (HR) of 100 beats·min^-1, with the CON testing occurring at the mid-point of the 3 h LONG condition. For all conditions, measures of left ventricular (LV) systolic [stroke volume, ejection fraction (EF), peak longitudinal strain, isovolumetric contraction time, S') and diastolic (E/A, E', isovolumetric relaxation time, longitudinal strain rate) function were reduced after exercise (all P < 0.05). In the right ventricle (RV), systolic function was reduced (tricuspid annular plane systolic excursion, S', peak longitudinal strain and strain rate) following all conditions, and fractional area change was reduced to the greatest degree following SIT (condition × time, P = 0.01). Females demonstrated lesser impairments in LV EF, and elastance (ESP/ESV) compared with males (P < 0.05). Markers of EICF occurred similarly following all cycling loads, suggesting the functional changes may be due to altered loading conditions and reduced stress-echocardiography workload. However, males experienced greater cardiac alterations in some measures, likely due to greater changes in postexercise loading conditions.NEW & NOTEWORTHY This investigation sought to determine the role of exercise intensity on the magnitude of exercise-induced cardiac fatigue using stress echocardiography to maintain loading conditions, with a secondary purpose of assessing sex differences. Unexpectedly, it was found that all cycling loads elicited the same magnitude of functional alteration, which likely represents a common response to exercise and stress echocardiography, rather than intrinsic cardiac impairment. Males demonstrated greater alterations than females, likely due to sex differences in postexercise hemodynamics.

Myocardial inefficiency is an early indicator of exercise-induced myocardial fatigue

Background

The effect of prolonged, high-intensity endurance exercise on myocardial function is unclear. This study aimed to determine the left ventricular (LV) response to increased exercise duration and intensity using novel echocardiographic tools to assess myocardial work and fatigue.

Materials and methods

LV function was assessed by echocardiography before, immediately, and 24 h after a cardiopulmonary exercise test (CPET) and a 91-km mountain bike leisure race. Cardiac Troponin I (cTnI) was used to assess myocyte stress.

Results

59 healthy recreational athletes, 52 (43-59) years of age, 73% males, were included. The race was longer and of higher intensity generating higher cTnI levels compared with the CPET (p < 0.0001): Race/CPET: exercise duration: 230 (210, 245)/43 (40, 45) minutes, mean heart rate: 154 ± 10/132 ± 12 bpm, max cTnI: 77 (37, 128)/12 (7, 23) ng/L. Stroke volume and cardiac output were higher after the race than CPET (p < 0.005). The two exercises did not differ in post-exercise changes in LV ejection fraction (LVEF) or global longitudinal strain (GLS). There was an increase in global wasted work (p = 0.001) following the race and a persistent reduction in global constructive work 24 h after exercise (p = 0.003).

Conclusion

Increased exercise intensity and duration were associated with increased myocardial wasted work post-exercise, without alterations in LVEF and GLS from baseline values. These findings suggest that markers of myocardial inefficiency may precede reduction in global LV function as markers of myocardial fatigue.

Syncope in the athlete - Minor changes, major diagnosis!

We report the case of a 17-year-old athlete who resorted to the emergency department for palpitations and dizziness while exercising. He mentioned two exercise-associated episodes of syncope in the last six months. He was tachycardic and hypotensive. The electrocardiogram showed regular wide complex tachycardia, left bundle branch block morphology with superior axis restored to sinus rhythm after electrical cardioversion. In sinus rhythm, it showed T-wave inversion in V1-V5. Transthoracic echocardiography revealed mild dilation and dysfunction of the right ventricle (RV) with global hypocontractility. Cardiac magnetic resonance (CMR) revealed a RV end diastolic volume indexed to body surface area of 180 ml/m², global hypokinesia and RV dyssynchrony, subepicardial late enhancement in the distal septum and in the middle segment of the inferoseptal wall. The patient underwent a genetic study which showed a mutation in the gene that encodes the desmocolin-2 protein (DSC-2), which is involved in the pathogenesis of arrhythmogenic right ventricular cardiomyopathy (ARVC). According to the modified Task Force Criteria for this diagnosis, the patient presented four major criteria for ARVC. Thus, a subcutaneous cardioverter was implanted, and the patient was followed up at the cardiology department. Arrhythmogenic right ventricular cardiomyopathy diagnosis is based on structural, functional, electrophysiological and genetic criteria reflecting underlying histological changes. This case depicts the essential characteristics for disease recognition.

Cardiac Events in World-Class Athletes: An Internet-Based Study

PURPOSE

This study aimed at assessing the prevalence of adverse cardiac events, as identified in the media, in world-class athletes according to their sex and sports discipline.

METHODS

All female and male athletes from 30 individual Olympic sports who ranked in the international yearly top 10 between 2006 and 2018 were included. The name of each of them was associated in a Google search with selected key terms related to heart disease and/or acute cardiac events after their inclusion date. Global and sex-specific adverse cardiac event hazard function λ were calculated for each sport. Global and sex-specific prevalences of cardiac events were calculated, then compared (Fisher's exact test) between all sports.

RESULTS

From the 2471 athletes included, 15 cases of cardiac events (prevalence of 0.61%) were reported; 2 sudden cardiac deaths (0.08%) occurred in male athletes. The other events were related to arrhythmic events ( n = 13), mainly supraventricular arrhythmias ( n = 9). All surviving athletes were able to continue their career, mostly after ablation procedure. Male endurance athletes accounted for seven events, among which three events occurred among short-distance triathletes. Events among women were comparatively rare ( n = 4), and all were observed among short-distance triathletes.

CONCLUSIONS

A relatively unexpected high prevalence of cardiac events in endurance elite athletes was observed as compared with other sports, mainly, in short-distance male and female triathletes. This raises the question of particular cardiovascular constraints in this discipline and underlines the urge of international longitudinal follow-up studies in these kinds of athletes.

Soldiers' Heart: A Prospective Study of Cardiac Remodeling in Soldiers Undergoing Progressive Intensity Exercise Training

PURPOSE

Most studies reporting cardiac changes with exercise have been cross sectional. The few available longitudinal studies have lacked standardization for environmental confounders. We prospectively assessed the relationship between increasing exercise intensity and cardiac remodeling in a highly standardized cohort of healthy young army soldiers.

METHODS

Sixty-three male army recruits (22 ± 3 yr) underwent a 12-wk moderate-intensity mixed strength and endurance exercise program, followed by a further 15-wk high-intensity exercise program, with highly controlled exercise, diet, and sleep patterns. Fitness (multistage fitness test), anthropometry, and 2D echocardiography were assessed.

RESULTS

Moderate-intensity exercise was associated with increased fitness and decreased body fat % (both P < 0.01). There was no significant incremental change in these parameters after high-intensity exercise. By contrast, both moderate- and high-intensity exercises were associated with dose-dependent increases in left atrial and left ventricular (LV) volumes, LV mass, and right ventricular (RV) size (all P < 0.01). At the end of high-intensity training, 51% had a dilated LV and 59% had a dilated RV compared with published normal ranges. Almost all had normal LV systolic function and strain before and after exercise training. A small number of soldiers had mildly decreased RV systolic function at baseline and after moderate-intensity exercise (3% and 6%, respectively).

CONCLUSIONS

We describe "soldiers' heart," which is characterized by balanced chamber dilatation, normal LV mass, and largely normal systolic function and myocardial strain. This prospective and highly controlled longitudinal study also found that increasing intensity exercise was associated with increasing chamber dimensions, which paralleled an increase in fitness after moderate-intensity exercise. After high-intensity exercise, however, cardiac chamber size continued to increase, but fitness did not increase further.

Prognostic value of acute cor pulmonale in COVID-19-related pneumonia: A prospective study

Background

It is known that acute cor pulmonale (ACP) worsens the prognosis of non-coronavirus disease 2019 (COVID-19) acute respiratory distress syndrome (NC-ARDS). The ACP risk score evaluates the risk of ACP occurrence in mechanically ventilated patients with NC-ARDS. There is less data on the risk factors and prognosis of ACP induced by COVID-19-related pneumonia.

Objective

The objective of this study was to evaluate the prognostic value of ACP, assessed by transthoracic echocardiography (TTE) and clinical factors associated with ACP in a cohort of patients with COVID-19-related pneumonia.

Materials and methods

Between February 2020 and June 2021, patients admitted to intensive care unit (ICU) at Amiens University Hospital for COVID-19-related pneumonia were assessed by TTE within 48 h of admission. ACP was defined as a right ventricle/left ventricle area ratio of >0.6 associated with septal dyskinesia. The primary outcome was mortality at 30 days.

Results

Among 146 patients included, 36% (n = 52/156) developed ACP of which 38% (n = 20/52) were non-intubated patients. The classical risk factors of ACP (found in NC-ARDS) such as PaCO₂ >48 mmHg, driving pressure >18 mmHg, and PaO₂/FiO₂ < 150 mmHg were not associated with ACP (all P-values > 0.1). The primary outcome occurred in 32 (22%) patients. More patients died in the ACP group (n = 20/52 (38%) vs. n = 12/94 (13%), P = 0.001). ACP [hazards ratio (HR) = 3.35, 95%CI [1.56–7.18], P = 0.002] and age >65 years (HR = 2.92, 95%CI [1.50–5.66], P = 0.002) were independent risk factors of 30-day mortality.

Conclusion

ACP was a frequent complication in ICU patients admitted for COVID-19-related pneumonia. The 30-day-mortality was 38% in these patients. In COVID-19-related pneumonia, the classical risk factors of ACP did not seem relevant. These results need confirmation in further studies.

Ventricular Flutter and Pleomorphic Ventricular Tachycardia-Induced Syncope in Borderline Arrhythmogenic Right Ventricular Cardiomyopathy

A 20-year-old female competitive collegiate swimmer presented after 2 postexercise syncopal episodes and 1 episode while actively swimming. Ambulatory monitoring and exercise testing revealed nonsustained ventricular tachycardia. Electroanatomic mapping demonstrated multifocal premature ventricular contractions and ventricular flutter originating from the right ventricular outflow tract, consistent with borderline arrhythmogenic right ventricular cardiomyopathy. (Level of Difficulty: Intermediate.).

Imaging in Pulmonary Vascular Disease-Understanding Right Ventricle-Pulmonary Artery Coupling

The right ventricle (RV) and pulmonary arterial (PA) tree are inextricably linked, continually transferring energy back and forth in a process known as RV-PA coupling. Healthy organisms maintain this relationship in optimal balance by modulating RV contractility, pulmonary vascular resistance, and compliance to sustain RV-PA coupling through life's many physiologic challenges. Early in states of adaptation to cardiovascular disease-for example, in diastolic heart failure-RV-PA coupling is maintained via a multitude of cellular and mechanical transformations. However, with disease progression, these compensatory mechanisms fail and become maladaptive, leading to the often-fatal state of "uncoupling." Noninvasive imaging modalities, including echocardiography, magnetic resonance imaging, and computed tomography, allow us deeper insight into the state of coupling for an individual patient, providing for prognostication and potential intervention before uncoupling occurs. In this review, we discuss the physiologic foundations of RV-PA coupling, elaborate on the imaging techniques to qualify and quantify it, and correlate these fundamental principles with clinical scenarios in health and disease. © 2022 American Physiological Society. Compr Physiol 12: 1-26, 2022.

Arrhythmogenic Cardiomyopathy: Exercise Pitfalls, Role of Connexin-43, and Moving beyond Antiarrhythmics

Arrhythmogenic Cardiomyopathy (ACM), a Mendelian disorder that can affect both left and right ventricles, is most often associated with pathogenic desmosomal variants that can lead to fibrofatty replacement of the myocardium, a pathological hallmark of this disease. Current therapies are aimed to prevent the worsening of disease phenotypes and sudden cardiac death (SCD). Despite the use of implantable cardioverter defibrillators (ICDs) there is no present therapy that would mitigate the loss in electrical signal and propagation by these fibrofatty barriers. Recent studies have shown the influence of forced vs. voluntary exercise in a variety of healthy and diseased mice; more specifically, that exercised mice show increased Connexin-43 (Cx43) expression levels. Fascinatingly, increased Cx43 expression ameliorated the abnormal electrical signal conduction in the myocardium of diseased mice. These findings point to a major translational pitfall in current therapeutics for ACM patients, who are advised to completely cease exercising and already demonstrate reduced Cx43 levels at the myocyte intercalated disc. Considering cardiac dysfunction in ACM arises from the loss of cardiomyocytes and electrical signal conduction abnormalities, an increase in Cx43 expression-promoted by low to moderate intensity exercise and/or gene therapy-could very well improve cardiac function in ACM patients.

Could Repeated Cardio-Renal Injury Trigger Late Cardiovascular Sequelae in Extreme Endurance Athletes?

Regular exercise confers multifaceted and well-established health benefits. Yet, transient and asymptomatic increases in markers of cardio-renal injury are commonly observed in ultra-endurance athletes during and after competition. This has raised concerns that chronic recurring insults could cause long-term cardiac and/or renal damage. Indeed, extreme endurance exercise (EEE) over decades has sometimes been linked with untoward cardiac effects, but a causal relation with acute injury markers has not yet been established. Here, we summarize the current knowledge on markers of cardiac and/or renal injury in EEE athletes, outline the possible interplay between cardiac and kidney damage, and explore the roles of various factors in the development of potential exercise-related cardiac damage, including underlying diseases, medication, sex, training, competition, regeneration, mitochondrial dysfunction, oxidative stress, and inflammation. In conclusion, despite the undisputed health benefits of regular exercise, we speculate, based on the intimate link between heart and kidney diseases, that in rare cases excessive endurance sport may induce adverse cardio-renal interactions that under specific, hitherto undefined conditions could result in persistent cardiac damage. We highlight future research priorities and provide decision support for athletes and clinical consultants who are seeking safe strategies for participation in EEE training and competition.

Right heart structure and function in lifelong recreational endurance athletes with and without paroxysmal atrial fibrillation

BACKGROUND

Healthy young athletes adapt to the increased demands of endurance exercise with symmetric cardiac remodeling. Male veteran endurance athletes have an increased risk of atrial fibrillation (AF), and some athletes seem susceptible to changes mimicking arrhythmogenic cardiomyopathy. Intense exercise puts a disproportionate hemodynamic load on the right-sided heart chambers. Despite this, data describing right heart structure and function in older veteran athletes are scarce. We aimed to investigate structural and functional characteristics of the right heart in veteran athletes with and without AF to contribute to the understanding of exercise-induced cardiac remodeling in this group.

METHODS

Three hundred and two male participants, of whom 151 were veteran skiers (62 with paroxysmal AF) and 151 were controls from the general population (62 with paroxysmal AF) underwent an echocardiographic examination in sinus rhythm to evaluate right atrial (RA) and right ventricular (RV) structure and function. While 87 of the participants had never exercised regularly, 50, 43, and 122 men had practiced regular endurance exercise for 1-20, 20-40, and >40 years, respectively.

RESULTS

RA volume and RV size increased with cumulative years of exercise (p<0.001), with a disproportionate increase in RV size compared with left ventricular (LV) size, regardless of AF status (p<0.001). RA and RV function assessed by strain remained similar despite lifelong exposure to endurance exercise. AF was associated with reduced RA strain irrespective of exposure to exercise (p<0.001).

CONCLUSION

RA and RV size and RV/LV ratio showed a dose-response relationship with cumulative years of endurance exercise, whereas RA and RV function did not. Indicating that increasing RV/LV ratio may represent a physiological adaptation to prolonged endurance exercise. AF was associated with reduced RA function, regardless of exposure to exercise, suggesting RA functional parameters are more closely linked to AF than RA size in veteran athletes.

Population Prevalence of Premature Truncating Variants in Plakophilin-2 and Association With Arrhythmogenic Right Ventricular Cardiomyopathy: A UK Biobank Analysis

BACKGROUND

Truncating variants in the desmosomal gene PKP2 (PKP2tv) cause arrhythmogenic right ventricular cardiomyopathy (ARVC) yet display varied penetrance and expressivity.

METHODS

We identified individuals with PKP2tv from the UK Biobank (UKB) and determined the prevalence of an ARVC phenotype and other cardiovascular traits based on clinical and procedural data. The PKP2tv minor allelic frequency in the UKB was compared with a second cohort of probands with a clinical diagnosis of ARVC (ARVC cohort), with a figure of 1:5000 assumed for disease prevalence. In silico predictors of variant pathogenicity (combined annotation-dependent depletion and Splice AI [Illumina, Inc.]) were assessed.

RESULTS

PKP2tv were identified in 193/200 643 (0.10%) UKB participants, with 47 unique PKP2tv. Features consistent with ARVC were present in 3 (1.6%), leaving 190 with PKP2tv without manifest disease (UKB cohort; minor allelic frequency 4.73×10-4). The ARVC cohort included 487 ARVC probands with 144 distinct PKP2tv, with 25 PKP2tv common to both cohorts. The odds ratio for ARVC for the 25 common PKP2tv was 0.047 (95% CI, 0.001-0.268; P=2.43×10-6), and only favored ARVC (odds ratio >1) for a single variant, p.Arg79*. In silico variant analysis did not differentiate PKP2tv between the 2 cohorts. Atrial fibrillation was over-represented in the UKB cohort in those with PKP2tv (7.9% versus 4.3%; odds ratio, 2.11; P=0.005).

CONCLUSIONS

PKP2tv are prevalent in the population and associated with ARVC in only a small minority, necessitating a more detailed understanding of how PKP2tv cause ARVC in combination with associated genetic and environmental risk factors.

Difference in cardiac remodeling between female athletes and pregnant women: a case control study

OBJECTIVES

The aim of this study was to detect possible differences in reversible cardiac remodeling occurring in sport training and twin pregnancy.

BACKGROUND

cardiac remodeling occurs in athletes and pregnant women due to training and fetal requirements, respectively. These changes could be apparently similar.

METHODS

21 female elite athletes (23.2 ± 5.3 years), 25 women with twin pregnancies (35.4 ± 5.7 years) and 25 healthy competitive female athletes (controls), age-matched with pregnant women (34.9 ± 7.9 years), were enrolled. This latter group was included to minimize the effect of age on cardiac remodeling. All women evaluated through anamnestic collection, physical examination, 12 leads ECG, standard echocardiogram and strain analysis. Sphericity (SI) and apical conicity (ACI) indexes were also calculated.

RESULTS

Pregnant women showed higher LA dimension (p < 0.001) compared to both groups of athletes. LV e RV GLS were significantly different in pregnant women compared to female athletes (p = 0.02 and 0.03, respectively). RV GLS was also different between pregnant women and controls (p = 0.02). Pregnant women showed significantly higher S' wave compared to female athletes (p = 0.02) but not controls. Parameters of diastolic function were significantly higher in athletes (p = 0.08 for IVRT and p < 0.001 for E/A,). SI was lower in athletes in both diastole (p = 0.01) and systole (p < 0.001), while ACIs was lower in pregnant women (p = 0.04).

CONCLUSIONS

Cardiac remodeling of athletes and pregnant women could be similar at first sight but different in LV shape and in GLS, highlighting a profound difference in longitudinal deformation between athletes and pregnant women. This difference seems not to be related with age. These findings suggest that an initial maternal cardiovascular maladaptation could occur in the third trimester of twin pregnancies.

Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) encompasses a group of conditions characterized by right ventricular fibrofatty infiltration, with a predominant arrhythmic presentation. First described in the late 1970s and early 1980s, it is now frequently recognized to have biventricular involvement. The prevalence is ∼1:2,000 to 1:5,000, depending on geographic location, and it has a slight male predominance. The diagnosis of ARVC is determined on the basis of fulfillment of task force criteria incorporating electrophysiological parameters, cardiac imaging findings, genetic factors, and histopathologic features. Risk stratification of patients with ARVC aims to identify those who are at increased risk of sudden cardiac death or sustained ventricular tachycardia. Factors including age, sex, electrophysiological features, and cardiac imaging investigations all contribute to risk stratification. The current management of ARVC includes exercise restriction, β-blocker therapy, consideration for implantable cardioverter-defibrillator insertion, and catheter ablation. This review summarizes our current understanding of ARVC and provides clinicians with a practical approach to diagnosis and management.

Multimodality Imaging in Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a rare, heritable myocardial disease associated with the development of ventricular arrhythmias, heart failure, and sudden cardiac death in early adulthood. Multimodality imaging is a central component in the diagnosis and evaluation of ARVC. Diagnostic criteria established by an international task force in 2010 include noninvasive parameters from echocardiography and cardiac magnetic resonance imaging. These criteria identify right ventricular structural abnormalities, chamber and outflow tract dilation, and reduced right ventricular function as features of ARVC. Echocardiography is a widely available and cost-effective technique, and it is often selected for initial evaluation. Beyond fulfillment of diagnostic criteria, features such as abnormal tricuspid annular plane excursion, increased right ventricular basal diameter, and abnormal strain patterns have been described. 3-dimensional echocardiography may also expand opportunities for structural and functional assessment of ARVC. Cardiac magnetic resonance has the ability to assess morphological and functional cardiac features of ARVC and is also a core modality in evaluation, however, tissue characterization of the right ventricle is limited by spatial resolution and low specificity for detection of pathological changes. Nonetheless, the ability of cardiac magnetic resonance to identify left ventricular involvement, offer high negative predictive value, and provide a reproducible structural evaluation of the right ventricle enhance the ability and scope of the modality. In this review, the prognostic significance of multimodality imaging is outlined, including the supplemental value of multidetector computed tomography and nuclear imaging. Strengths and weaknesses of imaging techniques, as well as future direction of multimodality assessment, are also described.

Advanced cardiac imaging in athlete's heart: unravelling the grey zone between physiologic adaptation and pathology

Over the last decades, interest toward athlete's heart has progressively increased, leading to improve the knowledge on exercise-induced heart modifications. Sport may act as a trigger for life-threatening arrhythmias in patients with structural or electrical abnormalities, hence requiring to improve the diagnostic capability to differentiate physiological from pathological remodeling. Pathological alterations are often subtle at the initial stages; therefore, the challenge is to promptly identify athletes at risk of sudden cardiac death during the pre-participation screening protocols. Advanced imaging modalities such as coronary computed tomography angiography (CCTA) and cardiac magnetic resonance (CMR) can non-invasively depict coronary vessels and provide a deep morpho-functional and structural characterization of the myocardium, in order to rule out pathological life threatening alterations, which may overlap with athletes' heart remodeling. The purpose of the present narrative review is to provide an overview of most frequent diagnostic challenges, defining the boundaries between athlete's heart remodeling and pathological structural alteration with a focus on the role and importance of CCTA and CMR.

Cardiac structure and function in elite female athletes: A systematic review and meta-analysis

We conducted a meta-analysis to synthesize the best available evidence comparing cardiac biventricular structure and function using cardiac magnetic resonance imaging (CMR) and transthoracic echocardiography (TTE) in elite female athletes and healthy controls (HC). Chronic exposure to exercise may induce cardiac chamber enlargement as a means to augment stroke volume, a condition known as the "athlete's heart." These changes have not been clearly characterized in female athletes. Multiple databases were searched from inception to June 18, 2019. Outcomes of interest included left ventricular (LV) and right ventricular (RV) dimensional, volumetric, mass, and functional assessments in female athletes. Most values were indexed to body surface area. The final search yielded 22 studies, including 1000 female athletes from endurance, strength, and mixed athletic disciplines. CMR-derived LV end-diastolic volume (LVEDV) and RV end-diastolic volume (RVEDV) were greater in endurance athletes (EA) versus HC (17.0% and 18.5%, respectively; both p < 0.001). Similarly, TTE-derived LVEDV and RVEDV were greater in EA versus HC (16.8% and 28.0%, respectively; both p < 0.001). Both LVEF and RVEF were lower in EA versus HC, with the most pronounced difference observed in RVEF via TTE (9%) (p < 0.001). LV stroke volume was greater in EA versus HC via both CMR (18.5%) and TTE (13.2%) (both p < 0.05). Few studies reported data for the mixed athlete (MA) population and even fewer studies reported data for strength athletes (SA), therefore a limited analysis was performed on MA and no analysis was performed on SA. This evidence-synthesis review demonstrates the RV may be more susceptible to ventricular enlargement. General changes in LV and RV structure and function in female EA mirrored changes observed in male counterparts. Further studies are needed to determine if potential adverse outcomes occur secondary to these changes.

Parameter estimation for closed-loop lumped parameter models of the systemic circulation using synthetic data

Physics-based models can be applied to describe mechanisms in both health and disease, which has the potential to accelerate the development of personalized medicine. The aim of this study was to investigate the feasibility of personalizing a model of systemic hemodynamics by estimating model parameters. We investigated the feasibility of estimating model parameters for a closed-loop lumped parameter model of the left heart and systemic circulation using the step-wise subset reduction method. This proceeded by first investigating the structural identifiability of the model parameters. Secondly we performed sensitivity analysis to determine which parameters were most influential on the most relevant model outputs. Finally, we constructed a sequence of progressively smaller subsets including parameters based on their ranking by model output influence. The model was then optimized to data for each set of parameters to evaluate how well the parameters could be estimated for each subset. The subsequent results allowed assessment of how different data sets, and noise affected the parameter estimates. In the noiseless case, all parameters could be calibrated to less than 10^-3% error using time series data, while errors using clinical index data could reach over 100%. With 5% normally distributed noise the accuracy was limited to be within 10% error for the five most sensitive parameters, while the four least sensitive parameters were unreliably estimated for waveform data. The three least sensitive parameters were particularly challenging to estimate so these should be prioritised for measurement. Cost functions based on time series such as pressure waveforms, were found to give better parameter estimates than cost functions based on standard indices used in clinical assessment of the cardiovascular system, for example stroke volume (SV) and pulse pressure (PP). Averaged parameter estimate errors were reduced by several orders of magnitude by choosing waveforms for noiseless synthetic data. Also when measurement data were noisy, the parameter estimation procedure based on continuous waveforms was more accurate than that based on clinical indices. By application of the step-wise subset reduction method we demonstrated that by the addition of venous pressure to the cost function, or conversely fixing the systemic venous compliance parameter at an accurate value improved all parameter estimates, especially the diastolic filling parameters which have least influence on the aortic pressure.

Facts and Gaps in Exercise Influence on Arrhythmogenic Cardiomyopathy: New Insights From a Meta-Analysis Approach

Arrhythmogenic cardiomyopathy (ACM) is a genetic cardiac condition characterized by fibrofatty myocardial replacement, either at the right ventricle, at the left ventricle, or with biventricular involvement. Ventricular arrhythmias and heart failure represent its main clinical features. Exercise benefits on mental and physical health are worldwide recognized. However, patients with ACM appear to be an exception. A thorough review of the literature was performed in PubMed searching for original papers with the terms “ARVC AND sports/exercise” and “sudden cardiac death AND sports/exercise.” Additional papers were then identified through other sources and incorporated to the list. All of them had to be based on animal models or clinical series. Information was structured in a regular format, although some data were not available in some papers. A total of 34 papers were selected and processed regarding sports-related sudden cardiac death, pre-clinical models of ACM and sport, and clinical series of ACM patients engaged in sports activities. Eligible papers were identified to obtain pooled data in order to build representative figures showing the global incidence of the most important causes of sudden cardiac death in sports and the global estimates of life-threatening arrhythmic events in ACM patients engaged in sports. Tables and figures illustrate their major characteristics. The scarce points of controversy were discussed in the text. Fundamental concepts were summarized in three main issues: sports may accelerate ACM phenotype with either structural and/or arrhythmic features, restriction may soften the progression, and these rules also apply to phenotype-negative mutation carriers. Additionally, remaining gaps in the current knowledge were also highlighted, namely, the applicability of those fundamental concepts to non-classical ACM phenotypes since left dominant ACM or non-plakophillin-2 genotypes were absent or very poorly represented in the available studies. Hopefully, future research endeavors will provide solid evidence about the safest exercise dose for each patient from a personalized medicine perspective, taking into account a big batch of genetic, epigenetic, and epidemiological variables, for instance, in order to assist clinicians to provide a final tailored recommendation.

Cardiac Biomarkers and Autoantibodies in Endurance Athletes: Potential Similarities with Arrhythmogenic Cardiomyopathy Pathogenic Mechanisms

The “Extreme Exercise Hypothesis” states that when individuals perform training beyond the ideal exercise dose, a decline in the beneficial effects of physical activity occurs. This is due to significant changes in myocardial structure and function, such as hemodynamic alterations, cardiac chamber enlargement and hypertrophy, myocardial inflammation, oxidative stress, fibrosis, and conduction changes. In addition, an increased amount of circulating biomarkers of exercise-induced damage has been reported. Although these changes are often reversible, long-lasting cardiac damage may develop after years of intense physical exercise. Since several features of the athlete’s heart overlap with arrhythmogenic cardiomyopathy (ACM), the syndrome of “exercise-induced ACM” has been postulated. Thus, the distinction between ACM and the athlete’s heart may be challenging. Recently, an autoimmune mechanism has been discovered in ACM patients linked to their characteristic junctional impairment. Since cardiac junctions are similarly impaired by intense physical activity due to the strong myocardial stretching, we propose in the present work the novel hypothesis of an autoimmune response in endurance athletes. This investigation may deepen the knowledge about the pathological remodeling and relative activated mechanisms induced by intense endurance exercise, potentially improving the early recognition of whom is actually at risk.

Efficacy and safety of riociguat in the treatment of chronic thromboembolic pulmonary arterial hypertension: A meta-analysis

BACKGROUND

Riociguat is a novel soluble guanylate cyclase stimulator, and has been widely used for the treatment of pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension (CTEPH). Some studies found that riociguat had better effects on CTEPH and proved to be safe, but the results were not utterly consistent. Therefore, the purpose of this study was to comprehensively evaluate the efficacy and safety of riociguat in the treatment of CTEPH.

METHODS

Randomized controlled trials on riociguat for the treatment of CTEPH were searched through such electronic databases as PubMed, Embase, Cochrane Library, Web of Science, China national knowledge internet, and Wanfang. The outcomes included exercise capacity, pulmonary hemodynamics, and side effects. The fixed-effects or random-effects models were used to analyze the pooled data, and heterogeneity was assessed by the I2 test.

RESULTS

Four studies involving 520 patients were included in this meta-analysis. Compared with the placebo group, riociguat significantly improved the hemodynamic indexes and increased 6-min walking distance (P < .0001, standardized mean difference (SMD) = -0.24, 95%CI -0.35 to -0.12; P < .00001, SMD = 0.52, 95%CI 0.33 to 0.71), and decreased the Borg dyspnea score (P = .002, SMD = -0.31, 95%CI -0.51 to -0.12). In addition, riociguat could also significantly reduce the living with pulmonary hypertension scores and increase the EQ-5D scores (P = .01, SMD=-0.23, 95%CI -0.42 to -0.05; P < .00001, SMD = 0.47, 95%CI 0.27 to 0.66), but there was no significant difference in the change level of N-terminal pro-hormone B-type natriuretic peptide in patients with riociguat (P = .20, SMD = -0.24, 95%CI -0.61 to -0.13). The common adverse events of riociguat were dyspepsia and peripheral edema, and no other serious adverse reactions were observed.

CONCLUSIONS

We confirmed that riociguat had better therapeutic effects in improving the hemodynamic parameters and exercise capacity in patients with CTEPH without inducing serious adverse events. This will provide a reasonable medication regimen for the treatment of CTEPH.

Left Ventricular Fibrosis in Middle-Age Athletes and Physically Active Adults

INTRODUCTION

Cardiac magnetic resonance (CMR) late gadolinium enhancement (LGE) and T1 mapping techniques enable the quantification of focal and diffuse myocardial LGE, respectively. Studies have shown evidence of fibrosis in middle-age athletes, but not relative to physically active (PA) adults who perform recommended physical activity levels. Therefore, we examined cardiac remodeling and presence of left ventricular (LV) LGE and T1 values in both recreational middle-age endurance athletes (EA) and PA adults.

METHODS

Healthy EA and PA adults (45-65 yr) completed a standardized 3-T CMR protocol with ventricular volumetry, LV LGE, and T1 mapping.

RESULTS

Seventy-two EA and 20 PA participants (mean age, 53 ± 5 vs 56 ± 4 yr; P < 0.01; V˙O2peak = 50 ± 7 vs 37 ± 9 mL·kg·min, P < 0.0001) were examined, with CMR data available in 89/92 participants. Focal LV LGE was observed in 30% of participants (n = 27/89): 33% of EA (n = 23/69; 33%) and 20% of PA (n = 4/20; 20%). LGE was present at the right ventricular hinge point (n = 21/89; 23.5%) or identified as ischemic (n = 2/89; 2%) or nonischemic (n = 4/89; 4%). Focal LV LGE was observed similarly in both EA and PA (P = 0.25). EA had larger LV chamber sizes and T1 native values (1169 ± 35 vs 1190 ± 26, P = 0.02) compared with PA, with similar LV ejection fraction. Global extracellular volume (ECV) was similar in both EA and PA (22.6% ± 3.5% vs 21.5% ± 2.6%, P = 0.26), with no relationship between global ECV and LV mass (r = -0.16, P = 0.19).

CONCLUSIONS

Focal LGE at the right ventricular hinge point was detected at the same frequency in both groups, was unrelated to demographic or clinical indices, and was found without evidence of global ECV expansion in EA, suggesting a physiologic remodeling response. The long-term clinical implications of hinge-point LGE require clarification using prospective, long-term follow-up studies.

Exercise alters cardiac function independent of acute systemic inflammation in healthy men

Acute elevations in inflammatory cytokines have been demonstrated to increase aortic and left ventricular stiffness and reduce endothelial function in healthy subjects. As vascular and cardiac functions are often transiently reduced following prolonged exercise, it is possible that cytokines released during exercise may contribute to these alterations. The a priori aims of this study were to determine whether vaccine-induced increases in inflammatory cytokines would reduce vascular and left ventricular function, whether vascular alterations would drive cardiac impairments, and whether this would be potentiated by moderate exercise. In a randomized crossover fashion, 16 male participants were tested under control (CON) and inflammatory (INF) conditions, wherein INF testing occurred 8 h following administration of an influenza vaccine. On both days, participants underwent measures of echocardiography performed during light cycling (stress-echocardiography), carotid-femoral pulse wave velocity (cf-PWV), and superficial femoral flow-mediated dilation (FMD) before and after cycling for 90 min at ∼85% of their first ventilatory threshold. IL-6 increased significantly (Δ1.9 ± 1.3 pg/mL, P < 0.001), whereas TNFα was nonsignificantly augmented (Δ0.05 ± 0.11 pg/mL, P = 0.09), 8 h following vaccination. Vascular function was unaltered following cycling or inflammation (all P > 0.05). The use of echocardiography during light cycling revealed cardiac alterations traditionally expected to occur only with greater exercise loads, with reduced systolic (e.g., longitudinal strain CON: Δ3.3 ± 4.4%, INF: Δ1.7 ± 2.7%, P = 0.002) and diastolic function (e.g., E/A ratio CON: Δ-0.32 ± 0.34 a.u., INF:Δ-0.25 ± 0.27 a.u., P = 0.002) following cycling, independent of inflammation. The vaccine reduced stroke volume (SV) (main effect of condition P = 0.009) before-and-after cycling. These findings indicate that reduced cardiac function following exercise occurs largely independent of additional inflammatory load.NEW & NOTEWORHTHY This experimental investigation sought to determine the role of inflammation on the occurrence of cardiovascular alterations following exercise. Despite successfully stimulating systemic inflammation via vaccination, vascular and cardiac functions were largely unaltered. Prolonged exercise itself reduced cardiac function assessed via echocardiography performed during light exercise stress. This demonstrates a potential advantage to using stress-echocardiography for measuring exercise-induced cardiac fatigue, as typical resting measures following similar exercise exposures commonly suggest no effect.

Biventricular function in exercise during autonomic (thoracic epidural) block

BACKGROUND

Blockade of cardiac sympathetic fibers by thoracic epidural anesthesia (TEA) was previously shown to reduce right and left ventricular systolic function and effective pulmonary arterial elastance. At conditions of constant paced heart rate, cardiac output and systemic hemodynamics were unchanged. In this study, we further investigated the effect of cardiac sympathicolysis during physical stress and increased oxygen demand.

METHODS

In a cross-over design, 12 patients scheduled to undergo thoracic surgery performed dynamic ergometric exercise tests with and without TEA. Hemodynamics were monitored and biventricular function was measured by transthoracic two-dimensional and M-mode echocardiography, pulsed wave Doppler and tissue Doppler imaging.

RESULTS

TEA attenuated systolic RV function (TV S': - 21%, P < 0.001) and LV function (MV S': - 14%, P = 0.025), but biventricular diastolic function was not affected. HR (- 11%, P < 0.001), SVI (- 15%, P = 0.006), CI (- 21%, P < 0.001) and MAP (- 12%, P < 0.001) were decreased during TEA, but SVR was not affected. Exercise resulted in significant augmentation of systolic and diastolic biventricular function. During exercise HR, SVI, CI and MAP increased (respectively, + 86%, + 19%, + 124% and + 17%, all P < 0.001), whereas SVR decreased (- 49%, P < 0.001). No significant interactions between exercise and TEA were found, except for RPP (P = 0.024) and MV E DT (P = 0.035).

CONCLUSION

Cardiac sympathetic blockade by TEA reduced LV and RV systolic function but did not significantly blunt exercise-induced increases in LV and RV function. These data indicate that additional mechanisms besides those controlled by the cardiac sympathetic nervous system are involved in the regulation of cardiac function during dynamic exercise. Trial registration Clinical trial registration: Nederlands Trial Register, NTR 4880 http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=4880 .

Exercise restores dysregulated gene expression in a mouse model of arrhythmogenic cardiomyopathy

AIMS

Arrhythmogenic cardiomyopathy (ACM) is a myocardial disease caused mainly by mutations in genes encoding desmosome proteins ACM patients present with ventricular arrhythmias, cardiac dysfunction, sudden cardiac death, and a subset with fibro-fatty infiltration of the right ventricle predominantly. Endurance exercise is thought to exacerbate cardiac dysfunction and arrhythmias in ACM. The objective was to determine the effects of treadmill exercise on cardiac phenotype, including myocyte gene expression in myocyte-specific desmoplakin (Dsp) haplo-insufficient (Myh6-Cre:DspW/F) mice.

METHODS AND RESULTS

Three months old sex-matched wild-type (WT) and Myh6-Cre:DspW/F mice with normal cardiac function, as assessed by echocardiography, were randomized to regular activity or 60 min of daily treadmill exercise (5.5 kJ work per run). Cardiac myocyte gene expression, cardiac function, arrhythmias, and myocardial histology, including apoptosis, were analysed prior to and after 3 months of routine activity or treadmill exercise. Fifty-seven and 781 genes were differentially expressed in 3- and 6-month-old Myh6-Cre:DspW/F cardiac myocytes, compared to the corresponding WT myocytes, respectively. Genes encoding secreted proteins (secretome), including inhibitors of the canonical WNT pathway, were among the most up-regulated genes. The differentially expressed genes (DEGs) predicted activation of epithelial-mesenchymal transition (EMT) and inflammation, and suppression of oxidative phosphorylation pathways in the Myh6-Cre:DspW/F myocytes. Treadmill exercise restored transcript levels of two-third (492/781) of the DEGs and the corresponding dysregulated transcriptional and biological pathways, including EMT, inflammation, and secreted inhibitors of the canonical WNT. The changes were associated with reduced myocardial apoptosis and eccentric cardiac hypertrophy without changes in cardiac function.

CONCLUSION

Treadmill exercise restored transcript levels of the majority of dysregulated genes in cardiac myocytes, reduced myocardial apoptosis, and induced eccentric cardiac hypertrophy without affecting cardiac dysfunction in a mouse model of ACM. The findings suggest that treadmill exercise has potential beneficial effects in a subset of cardiac phenotypes in ACM.